In order to explore the changes in antioxidant activity of proteins after simulating gastrointestinal digestion in vitro， in this paper， ovalbumin was used as the research object， firstly， in vitro antioxidant activity of digested products were measured， then， H2O2 was used to construct a model of Caco-2 cell oxidative damage， and the cell viability and reactive oxygen species （ROS） levels were measured to investigate the cellular antioxidant activity of the products. Finally， electrospray orbital trap tandem mass spectrometry was used to identify three antioxidant peptides from the component with the strongest antioxidant activity （product with a molecular weight of less than 1 ku）. The results showed that after the ovalbumin was simulated in the gastrointestinal tract in vitro， the antioxidant activity of the product was enhanced in a concentration-dependent manner， and the smaller the molecular weight of the component， the stronger the antioxidant activity. Products with a molecular weight of <1 ku have the strongest ability to inhibit oxidative damage of cells and scavenge reactive oxygen species. The three peptide sequences identified by mass spectrometry all have strong antioxidant activity. The sequences are： CFDV， CVSP and MPFR. The above results show that in vitro simulated gastrointestinal digestion has a positive effect on the improvement of ovalbumin antioxidant activity and the release of antioxidant active peptides.